/*
 * @(#)$Id: LRUMap.java 3619 2008-03-26 07:23:03Z yui $
 * 
 * Copyright 2006-2008 Makoto YUI
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 * 
 * Contributors: Makoto YUI - initial implementation
 */
package jacky.lanlan.song.collection;

import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.util.LinkedHashMap;
import java.util.Map.Entry;

/**
 * 
 * <DIV lang="en"></DIV> <DIV lang="ja"></DIV>
 * 
 * @author Makoto YUI (yuin405+xbird@gmail.com)
 */
public class LRUMap<K, V> extends LinkedHashMap<K, V> {
	private static final long serialVersionUID = 1L;

	protected final int maxCapacity;

	public LRUMap(int maxCapacity) {
		super(maxCapacity, 1.0f, true);
		this.maxCapacity = maxCapacity;
	}

	@Override
	protected boolean removeEldestEntry(Entry<K, V> eldest) {
		return size() > maxCapacity;
	}

	public void writeTo(ObjectOutput out) throws IOException {
		out.writeInt(maxCapacity);
		int size = size();
		out.writeInt(size);
		for (Entry<K, V> e : entrySet()) {
			out.writeObject(e.getKey());
			out.writeObject(e.getValue());
		}
	}

	@SuppressWarnings("unchecked")
	public static <K, V> LRUMap<K, V> readFrom(ObjectInput in) throws IOException, ClassNotFoundException {
		int cap = in.readInt();
		final LRUMap<K, V> map = new LRUMap<K, V>(cap);
		final int size = in.readInt();
		for (int i = 0; i < size; i++) {
			K key = (K) in.readObject();
			V value = (V) in.readObject();
			map.put(key, value);
		}
		return map;
	}

}
